prospects on identified particle correlation in alice

Levente Molnar, INFN-Bari, KFKI-RMKI

March, 2007, Jyväskylä 1

Prospects on identified particle correlation in ALICE

Levente MolnarINFN-Bari, KFKI-RMKI



RHIC results on particle ratiosPHENIX, PRL 91, 172301

• Enhanced baryon/meson ratio in 200 GeV Au+Au collisions • (Anti-)proton-pion ratio above fragmentation, ...• Limited intermediate pT window

STAR, PRL 97,152301



Soft and hard interplay at RHIC

• Particle spectra, RCP and particle ratios are “well” described by soft and hard component models:

• Recombination + fragmentation• Hydro + jets• Hydro + pQCD• Soft + quenched

Fries,Muller, PRL90 202303, PRCC 68 044902



Soft and hard interplay at LHC

• The relative soft + hard contribution changes at higher energies:

• Recombination predictions…

• How well do we know the hard component?

• Measure p+p baseline …

Fries R. J.,Müller B. Eur. J. Phys. C 34 S279

LHC: Pb+PbR.Hwa, PRL97,04230



Contribution of quark and gluon jets in p+p

• Good description at 200GeV

200 G

eV

STAR, PLB 637,161

Λ K0

S. Albino et al., NPB 597,337

• Missing higher energy: 630 GeV

• PID in jet correlations



Particle correlations at RHICSTAR, nucl-ex/0601042

Two particle correlations in the intermediate pT region with trigger particle (4 <pT

trig<6 GeV/c ) exhibit:

• broadening of away side correlation (0.15<pT

assoc<4.0 GeV/c)

• suppression of high pT particles in central Au+Au collisions (2 GeV/c <pT

assoc<pTtrig)F.Wang,NPA783,157, L.M. nucl-ex/0701061

Mid-rapidity Forward-rapidity Mid-rapidity

STAR, 91 (2003) 072304 STAR, 91 (2003) 072304



Particle correlations at RHIC II.

• Presence of long range ∆η correlations

• Extends to forward rapidities?

• Particle composition of “bulk” and “ridge”, ongoing effort at RHIC

STAR, nucl-ex/0601042

F.Wang,NPA783,157, L.M. nucl-ex/0701061

J.Putschke, QM’06

Au+Au 200GeV0-10%



Particle correlations at RHIC III.STAR, nucl-ex/0601042

Au+Au Central 0-12% Triggered

J.Ulery, IWCF’06

N.Ajitanand IWCF’06• Identified particles in the cone region, similarly to “ridge” measurements

M.Ploskon



ITSLow pt trackingVertexing

ITSLow pt trackingVertexing

TPCTracking, dEdxTPCTracking, dEdx

TRDElectron IDTRDElectron ID

TOFPIDTOFPID

HMPIDPID (RICH) @ high pt

HMPIDPID (RICH) @ high pt

PHOS,0 PHOS,0

MUON -pairs MUON -pairs

PMD multiplicityPMD multiplicity

V0, T0Trigger + multiplicity

ACORDEcosmics

FMDch multiplicityFMDch multiplicity

EM Calorimeter

The ALICE detector

First run setup:• ITS, TPC, MUON• HMPID• 10-15% TRD• 50% ToF



• Low magnetic field (0.2-0.5T)

• Wide momentum range (tracking): ~ 100 MeV up to >100 GeV

• Strong PID capabilities in the central region (|η|<0.9)

Particle identification in ALICE

• Direct hadron PID: (p, K, p) up to ~ 5 GeV, rdEdx ~ 50 GeV/c

• Photons, Leptons

• Topological PID up to ~ 20 GeV/c

separation @ 3 separation @ 2

EMCAL

ALICE PPR II, JPG 32,1295



Multiplicity at the Tevatron and LHCW.D.Walker PRD 69, 034007

• Increasing cms. energy, broken KNO scaling

Nch

900GeV

14TeV5.5TeV

2.2TeV

Probability for an event to have larger than Nch multiplicity

(||<0.9)

T.Nayak, QM’06

At LHC: • further multiplicity reach• study multi-parton interactions• dedicated high multiplicity trigger (?)



Soft and hard events a la CDF

• EMCAL+tracking (|η|<1.2)

• In a cone R = 0.7 define (EMCAL + tracking)

• Soft events: – no cluster with ET > 1.1 GeV

• Hard events:– ET seed >= 1.0 GeV or track with pT >= 0.7 GeV/c

– ET adj. > 0.1 GeV or track with pT > 0.4 GeV/c

CDF, PRD65, 072005



Soft and hard events a la CDF II.

(CDF) conclusions:

• Momentum distribution of “soft” events depends on Nch not on √s

• <pT> scales with √s

CDF, PRD65, 072005



Soft and hard events a la CDF III.

CDF, hep-ex/0504048

• The soft production of Λ0 and K0

S similar



High multiplicity trigger

D.Elia

ITS/SPD

HMPID

• Enhance high multiplicity events

• Limited HMPID : PID acceptance: fastOR trigger of SPD layers

• LHC commissioning …



Identified particles at Tevatron

E735, PRD48,984

B. Hippolyte, EPJ. C49:121-124,2007 STAR, nucl-ex/0607033

• Mapping identified particles in pT, Nch at each possible energies.



Particle correlations at ALICE

• Full jet reconstruction possible event by event:

• ETmin ~ 40 GeV

• jet fragments: pT ~ 2GeV/c

• RHIC results: statistical approach

• LHC: • enhanced yield of leading hadrons• but increase in comb. background

• How does it look like?



Charged hadron correlations in ALICE

• Significant away side at low pTassoc in 5.5TeV PbPb.

Appelshäuser H and Ploskon M 2005 ALICE-INT-2005-49



Particle correlations at ALICE

• Full jet reconstruction possible event by event:

• ETmin ~ 40 GeV

• jet fragments: pT ~ 2GeV/c

• RHIC results: statistical approach

• LHC: • enhanced yield of leading hadrons• but increase in comb. background

Focus on the near side: full PID for leading and associated particle(s)

• ITS+TPC+ToF+TRD (full azimuth, |η|<0.9)

• HMPID (57.61º in azimuth, |η|<0.6, track-by-track PID)



PID Particle correlations at ALICELeading particle correlations:

• trigger bias, determination of Ejet,

swing of away side parton, …

γ – PID correlations:

• measures Ejet, fix direction• low pT limit

Utilize ALICE geometry → PID

• PHOS module opposite to HMPID + ITS/TPC/TRD/ToF

• Adjacent to EMCAL+PHOS map out the underlying events

• PID of leading and assoc. particles: dial q/g jets? • Measure resonance particles



Summary

• RHIC results show a “complicated” intermediate pT region in HI collisions

• p+p measurement at the same cms energy are essential baseline to interpret HI collision

• PID (γ/h) correlations could provide more refined tools

• First data in ~ 8 months …

prospects on identified particle correlation in alice

Documents

pid particle correlations

pid correlations

trigger particle

rhictwo particle correlations

particle ratios

rhic particle spectra

gevparticle correlations

rhicparticle correlations